Surgical instrument



March 25, 1969 E. R. THOMAS, JR 3,434,477

SURGICAL INSTRUMENT Filed Nov. 23, 1966 FIG-l FIG-3 I5 FIG-2 FIG l 3e w 36 86 ll 28 y I a k [8 :1 74 v v H 73 e2 I4-A H 38 I 63 '1: j 64 32 67 22 ii FIG-7 71 68 2e 3 7o 88 88 83 77 INVENTOR. 2] w l6 EDWARD R. THOMAS,JR.

ATTORNEYS March 25, 1969 E. R. THOMAS, JR 3, 3

SURGICAL INSTRUMENT Filed Nov. 23. 1966 Sheet 3 of 2 H5 IZZ I2 /27 I32 lzo 1/7 120 12/ 141/42 [44 #73145 J l l l United States Patent 3,434,477 SURGICAL INSTRUMENT Edward R. Thomas, Jr., Bethesda, Md., assignor to Northwestern University, Evanston, Ill. Filed Nov. 23, 1966, Ser. No. 596,705 Int. Cl. A61b 17/36 US. Cl. 128303.1 19 Claims This invention relates to surgical equipment and more particularly to instruments for cryosurgery.

Very cold temperatures have come into acceptance for many surgical operations and treatment, both on humans and animals. For example, cryosurgery is being used for treating brain tumors, for removing cataracts from the eyes, as well as for repairing detached retinas. In order to achieve the very low temperatures required for this surgery, the equipment is generally very complex, bulky and heavy. It is difficult for the surgeon to master the operation of the apparatus without a complete understanding of the operation thereof thus impeding its acceptance. The hand piece utilized to apply the cold temperatures is frequently very large in diameter in order to provide the proper insulation so that the cold temperatures are not transmitted to the surgeons hand as well as to provide for the controlled flow of refrigerant. The hand piece is connected to a console by one or more conduits which usually include the tubes for the flow of refrigerant, as well as the electrical connectors for the sensors and heating mechanism.

Accordingly, an object of the invention is to provide an improved cryosurgical instrument which can be completely separated from the source of refrigerant for easy handling, or which may remain attached to the source for storage.

A further object of this invention is to provide a selfcontained cryosurgical system which includes a small base having a supply of refrigerant therein and a hand piece which is normally stored on the base and which is adapted for use in a plurality of surgical operations.

lAl'lOthCI' object of this invention is to provide an improved cryosurgical instrument which is provided with a novel heat sink which maintains sufficiently cold temperatures to perform the cataract removal operation, retinal detachment procedures and the like.

A further object of the invention is to provide an improved cryosurgical instrument wherein a filter is provided for insuring that all liquified refrigerant is evaporated prior to use of the instrument, and further to provide such an instrument wherein a plurality of probes of different shapes and configurations can be removably mounted.

Other objects and advantages of the invention will be apparent from the following description, the accompanying drawings and the appended claims.

In the drawings- FIG. 1 is a perspective view showing a surgeon using the surgical apparatus constructed in accordance with this invention;

FIG. 2 is a sectional view through the base portion of the surgical apparatus;

FIG. 3 is a sectional view through the surgical instrument portion of the apparatus;

FIG. 4 is an enlarged view of the heat sink;

FIG. 5 is an elevational view partially in section of one form of a probe which can be used on the hand piece;

FIG. 6 is a sectional view of the manner in which the hand piece actuates the valve on the base;

FIG. 7 is an end view of the valve actuating apparatus;

FIG. 8 is a sectional view similar to FIG. 3 but showing another embodiment of the invention;

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FIG. 9 is a sectional view similar to FIG. 8 showing another embodiment of the invention;

FIG. 10 is a sectional view taken along the line 10-10 of FIG. 9;

FIG. 11 is a sectional view illustrating a cap assembly which can be utilized to discharge the apparatus assembly;

FIG. 12 is a view similar to FIG. 11 showing another form of the cap assembly;

FIG. 13 is a sectional view of another form of the base which can be used with the several instruments;

FIG. 14 is a sectional view of another form of the instrument; and

FIGS. 1517 are elevation views of various forms of probes which can be utilized with the present invention.

Referring to the drawnigs wherein preferred embodiments of the invention are shown, FIG. 1 illustrates a surgeon 10 who is able to remove the lens of the eye of the patient 11 on the operating table 12. This is the cataract operation and it should be understood that the invention is not limited to this particular operation and the apparatus may be used to form other surgical opera tions, i.e. retinal detachments.

The surgical apparatus includes the small base 14 which provides a source of refrigerant and a holder for the hand piece or surgical instrument 15. As shown in FIG. 2, the small base 14 includes a cup-shaped lower member 16 which receives and supports the frustoconical body 17 havnig the cap 18 mounted on top thereof. The body 17 has a plurality of downwardly extending legs 21 which engage the upper surface 22 of the cup member 16 and the screw 23 extends through the opening 24 in the cup member into a central threaded bore in the horizontal partition 26 within the body 17. The body 17 receives commercial container 28 of liquid refrigerant, such as Freon, which has a valve member 30 mounted in the top thereof adapted to discharge the liquid refrigerant, as will be described. The container 28 is held firmly in position by the annular member 32 which is secured to the partition 26.

The cap 18 has upstanding neck 35 (FIG. 6) in the central portion thereof having an O-ring 36 (FIG. 6) around the outer periphery thereof for fluid tight contact with the lower end of the surgical instrument 15. Referring now to FIG. 3 which illustrates a preferred embodiment of the surgical instrument 15, the instrument comprises an elongated tubular housing 40 of relatively small diameter so that it can be handled by the surgeon in much the same manner as a pencil. The housing 40 may be made of metal, porous plastic or a plastic material such as Teflon or silicone which is an excellent heat insulator thereby protecting the surgeons hands from the cold temperatures. The heat sink 41 is provided in the upper end of the housing, and this heat sink has a solid metallic frustoconical portion 42 with a plurality of axial extending projections 43 thereon as shown in FIGS. 3 and 4.

The apex 45 of the housing has an opening therein so that the threaded extension 46 of the probe 47 can extend therethrough into a complementary bore 48 within the heat sink. Accordingly, heat or cold is quickly transferred from the heat sink into the probe 47. The probe 47 shown in FIGS. 3 and 5 includes a solid elongated section 51 having a beveled tip 52 on one end thereof and a knurled flange 53 and the threaded extension 46 on the other end thereof. The outer portion of the elongated section 51 is covered by a plastic insulator 55, such as Teflon, to insure maximum transfer of the heat to the beveled tip 52 of the probe 47 The valve mechanism 60 on the base 14 and container 28 is shown in FIG. 6 and includes an upwardly extending tubular member 61 secured in the neck 62 on top of the container 28. The lower end of this tube forms a valve seat 62 against which the valve member 64 is forced by the pin 65 and the spring 66 which is disposed between the head 67 of the pin 65 and the shoulder 68 formed on top of the discharge tube 70.

The discharge tube 70 is held also within container 28 by the intermediate collar 71 which is secured to the neck 62 and extends downwardly into the container a short distance to support the discharge tube 70. The valve member 64 has an upwardly extending actuator rod 73 which extends through the tube 61, as shown in FIG. 6. The guide member 74 may be provided on the upper end of this tube to insure that it is centered in the tube 61 at all times. When the cap 18 is placed on the body 17, the tube 61 extends upwardly into the passage 75 within the neck 35 and is sealed by the O-ring seal 36 so that fluid does not flow between the outer portion of the tube 61 and the inner surface of the passage 75. The instrument may be removably locked to the base by suitable means (not shown) to prevent it from being accidentally separated from the base.

When the instrument 15 is pressed onto the neck 35, it is spaced above the top surface 76 of the cap 18 since the actuator pin 77 in the instrument 15 engages the top of the actuator rod 73 and thus does not permit the instrument to be moved downwardly until sufficient force is provided to overcome the bias of the spring 66. In this condition, the instrument 15 is held in a storage position on the base 14. However, when the surgeon is about to utilize the instrument, one of his aids merely forces the instrument downwardly onto the neck 35 with a slight amount of additional pressure causing the actuator pin 77 to force the rod 73 downwardly to unseat the valve 64 which permits the liquid refrigerant to flow upwardly through the discharge tube 70, around the pin 65 and valve 64, and into the tube 61. The liquid continues to flow around the actuator pin and into the very small diameter transfer tube 80 in the hand piece. The transfer tube 80 is secured in the instrument 15 by the brackets 81 and 82 near the opposite ends thereof with the outermost bracket 82 having an axial projection 83 which supports the actuator pin 77 (FIG. 6) in the housing 40.

The refrigerant remains as a liquid as it flows through the tubes as it provides no substantial expansion thereof. However, when the liquid reaches the end of the transfer tube 80 it is sprayed from the outwardly flared end 80a onto the axial projections 43 of the heat sink 42 causing the liquid to expand immediately and vaporize with a very substantial loss of temperature thereby cooling the heat sink. The expanded gases then flow from the instrument 40 through openings 85 in the transfer tube supports 81 and 82, and are returned to the base 14 through the passages 86 in the neck 35, as shown in FIG. 6. The gases then .flow through the base 14, around the container 28 and through the vertical passages 88 (FIG. 2) in the partition 18.

The space 90 below the partition 18 is open to the atmosphere and thus the inert gas is exhausted. A suitable sponge material 92 may be provided in the space between the partition 18 and the surface 22 of the cup member 16 to spread out and break up any droplets of liquid refrigerant which might pass through the passage 88. Thus, when a droplet of liquid passes into this filter material, it wets the large surface area of the material to increase the surface area of the droplet so that there is a substantially increased surface area to expedite evaporation. The upstanding walls 93 on the cup member further reduce the possibility of liquid refrigerant passing from the base 14 onto the operating table and possibly injuring a patient.

The heat sink 42 is such that it will be cooled to a very cold temperature quickly because of the very large surface area presented by the sides of the projections 43 and the opposite ends thereof. Since the outside surfaces of the heat sink are covered with the Teflon, nylon or Bakelite covering 40 1 and since the probe 47 is similarly covered, the only areas in which the cold temperatures are dissipated are through the end 52 of the probe 47 and through the projections 43 themselves. Because the interior of the instrument has been cooled including the transfer tube 80, and its supports 81 and 82, the heat leaving the heat sink through the projections is relatively low and, as a result, the tip 52 remains cold for several minutes which is more than sufficient to perform the cataract and many other surgical operations. The base 14 is sufliciently small that it sets on the operating table 12 adjacent the patient 11 without interference and so that the surgeon can easily return the instrument 15 to the storage position on the base 14.

Another embodiment of the surgical instrument is shown in FIG. 8, wherein the housing includes a metallic tubular member 117 having the heat sink 118 mounted in one end thereof. The tubular member 117 is surrounded by an insulation material 120, such as absestos or the like, which is in turn covered by a plastic material 121 which holds the insulation in place and improves the appearance and cleanliness of the instrument. The heat sink 118 is also frustoconical and has the recessed end 122 thereof against which the liquid refrigerant is sprayed. The transfer tube 124 is threadedly mounted within the tubular member 117 by the brackets 126 and 127. A ball-shaped spray nozzle 130 is provided at the discharge end of the transfer tube 124 thereof for vaporizing the refrigerant. Similarly, the probe 132 is quite similar to that described above except that the end portion 133 is curved and a rounded tip 134 is provided.

A further embodiment of the invention is shown in FIG. 9 which illustrates a surgical instrument provided with the capability of storing liquid refrigerant. Thus the instrument 140 includes a tubular housing 141 which preferably is constructed of Teflon or the equivalent so that the cold temperatures are not transferred to the surgeon's hands. The inner portion of the housing has a partition 142 therein which receives the transfer tube 144 having its other end supported by the insert 145 which is threadedly received within the right-hand end of the housing 141. A plug member 147 is secured to the left-hand end of the housing 141 to create the storage space 148 (FIG. 9) between the partition 142, while the insert 145 closes another space 150 in the housing. The space 150 holds a filter material 152, such as Zitex, a form of Teflon material, and this space is connected to the atmosphere through the passages in the insert 145, shown in FIG. 11. The insert also includes a normally closed valve 154 therein in communication with the transfer tube 144 and adapted to engage the base 14 to charge the instrument 140.

The probe 155 is supported on the plug member 147 by the fru'stoconical support 156 which is threadedly received within a bore 157 in this plug member. The tubular probe 155 has a rounded end portion 158 and an insulating jacket 161 therearound. A spray tube 163 is also supported by the plug member 147 and extends centrally through the tubular probe 155 to expand liquid refrigerant adjacent the tip 166. Thus the probe 165 can be replaced by unscrewing the frustoconical support 156 and separating the same from the plug member 147 and then replacing another probe. The plug member 147 also includes the small rotary on and off or metering valve 167 adapted to close normally the passage 168 in line with the tube 163.

In operation of the FIG. 9 embodiment, the instrument 141 is placed on the base 14 in much the same manner as described above so that the valve actuator 166 causes the valve 64 in the base to be opened to allow the liquid refrigerant to flow through the one way valve 154 and transfer tube 144 into the storage compartment 148. During the filling operation, the valve 167 is closed so that liquid fills the entire compartment 148. When the instrument 115 is separated from the base 14, the valve 154 automatically closes thus sealing liquid within the space 148 and the transfer tube 144.

When the surgeon is about to use the instrument 115,

he turns the valve 167 which allows the liquid refrigerant to flow through the tube 163 and be expanded adjacent the tip 166. The evaporated refrigerant then flows through the probe 155 and into the discharge passage 170 formed in the housing 141 and into the filter chamber 150. The filter material 152 assures that any liquid refrigerant will be vaporized since it spreads the liquid and increases it. surface area so that it quickly evaporate-s. The gas then passes through the openings 172 in the insert 145 to the atmosphere.

After operation is completed, and the surgeon desires tc discharge the unused liquid from the compartment it is merely necessary to open the valve 175 and/or attach the discharge safety member 174 (FIG. ll) to the righthand end of the instrument 115 to affect the discharge. Similar end closure 185 is shown in FIG. 12 and is adapted for use when the instrument 140 is separated from the base 14 but it does not discharge the refrigerant since it merely protects the gas contaminated parts of the charge assembly and closes the instrument 140. Specifically, the member 174 has a bayonet type 175 of engagement so that it can be firmly secured on the pins 176 on the tubular housing 141 causing the projection 177 to engage the valve 154 to open the valve and allow the liquid refrigerant to fiow into the space 178 created between the discharge member 174 and the insert 145. The O-ring seals 181 between the discharge member 174 and the inside surface of the housing 141 insures that all of the refrigerant either evaporates or flows through the passages 182 and into the filter pad 183 before being discharged to the atmosphere to insure that all of the refrigerant is evaporated and that no liquid is discharged from the instrument 115.

A further embodiment of the invention is shown in FIGS. 13 and 14 wherein a modified instrument 200 and base 201 are shown. Referring first to the base 201, a source 202 of refrigerant exterior to the base 201 is utilized and is connected through the conduit 203 having the valve 204 therein to the metal tube 205 in the base 201. This tube extends vertically through the neck 206 in the base upwardly a substantial distance to spray the refrigerant into the instrument 200. An electrical temperature sensor, thermistor, or thermocouple is provided in this embodiment and it includes the electrical conductor 210 extending from the temperature gage 211 through the base 201 upwardly to the male electrical connector 212 in the top surface of the cap 213 on the base 201.

The instrument 200 includes the elongated tubular housing 215, having the heat sink 216 in one end thereof with the probe 217 connected thereto. A flange portion 220 of the heat sink 216 forms the support for the uppermost end of the tube 205 whereas the removable bracket 222 is provided to align the lower portion of the tube 205. Thus, when the instrument 200 is placed on the base 201, the tube 205 extends through the bracket 222 and into the flange portion 220 of the heat sink so that the refrigerant is sprayed into the chamber 224 defined by the heat sink 216. Suitable openings are provided in the flange portions 220 so that the evaporated gas can escape. The temperaturesensing device 226, for example a thermistor, is mounted in the heat sink adjacent the probe 217 to sense the temperature thereof. This sensing device 226 is connected by the electrical conductor 227 to the female connector 228 which engages the male connector in the base 220 so that the temperature can be read on the control gage 230.

In operation, the surgeon places the instrument 200 on the base 201 and when it is ready for use the valve 204 is actuated by suitable means, for example a foot switch, thus allowing the refrigerant to flow through the conduit 203 into the tube 205 which extends through the instrument 200 and sprays the refrigerant onto the heat sink 216. The temperature gage 230 indicates the temperature within the heat sink and the probe 217 so that the surgeon can determine when the instrument is ready for use.

When the desired temperature is reached, the valve 204 is closed and the instrument removed from the base ready for use. During the cooling operation the exhausted gases pass through the instrument 200, the passages 232 in the neck 206 of the base 201, and into the interior 233 of the base. From the interior of the base they pass through the passages 234 into the filter material 235, and then to the atmosphere in substantially the same manner described above in connection with the FIG. 2 embodiment.

FIGS. 15 through 17 illustrate three additional embodiments of the probes. In FIG. 15 the probe 250 includes an elongated tubular portion 251 having a round ball 252 on the end thereof. In FIG. 16 the probe 250 has the lower portion 253 extending axially from the flange 254 and the outermost portion 255 is bent at an acute angle, whereas in FIG. 17 the probe 250b tapers gradually to a point 256. It should also be understood that the configuration of the various probes used can be varied to accommodate the surgery being performed. As new operations and changing techniques are developed this will undoubtedly produce various improvements in probe design. This is particularly true in the cryo-treatment of cryobiopsy and cryocauterization of the female organs.

Thus the invention has provided an improved cryosurgical instrument system wherein the instrument can be separated from the source of current so that the surgeon need not worry about conduits and the like extending from the instrument. The instrument can thus be maneuvered as easily as a pencil to facilitate the surgical operation. Moreover, the source of refrigerant for the instrument is a small compact base which can be safely placed on the operating table adjacent the patient without fear of injury to the patient and without consuming any substantial amount of space. The instrument and its base are simple in design for maximum dependability and minimum cost.

While the forms of apparatus herein described constitute preferred embodiments of the invention, it is to be understood that the invention is not limited to these precise forms of apparatus, and that changes may be made therein without departing from the scope of the invention which is defined in the appended claims.

What is claimed is:

1. A cryosurgical system for performing surgical operations using very cold temperatures comprising, a base, a small instrument adapted to be secured to said base, said instrument including an elongated tubular housing having a heat sink secured in one end thereof, a probe secured in said one end for transfer of heat from said heat sink, said base including means for supplying a liquid refrigerant, a valve assembly in said base for cooperation with said supply means, a neck in the exterior surface of said base adapted to receive and hold said instrument, actuator means extending through said neck for cooperation with said valve assembly, means for actuating said valve assembly to permit the liquid refrigerant to flow upwardly through said neck into said instrument, and transfer means for conducting the liquid refrigerant from said neck to a position adjacent said heat sink and for spraying said liquid refrigerant onto said heat sink to substantially reduce the temperature thereof.

2. A cryosurgical system as defined in claim 1 wherein passage means are provided in said instrument and said base for preventing the evaporated refrigerant sprayed onto said heat sink through the instrument and into said base.

3. Apparatus as defined in claim 2 wherein said passage means includes an opening in said neck in communication with the interior of said instrument, and a filter material disposed in said base for flow of refrigerant therethrough prior to being vented to the atmosphere to insure complete vaporization of the refrigerant.

4. A cryosurgical system as defined in claim 1 wherein said transfer means is a transfer tube mounted axially within the instrument and having a projection on the end thereof adapted to engage said valve assembly for opening said valve when said instrument is placed on said neck of said base and forced downwardly.

5. Apparatus as defined in claim 1 wherein said means for supplying a liquid refrigerant is a disposable container removably mounted in said base and having valve means therein adapted to cooperate with said actuator means for opening said valve.

6. Apparatus as defined in claim 1 wherein said probe is removably secured to said heat sink.

7. A cryosurgical system as defined in claim 1 wherein said heat sink has a plurality of axially extending projections thereon which extend in the direction of said transfer means to increase the area of contact with the refrigerant to expedite cooling of said heat sink.

8. A cryosurgical system as defined in claim 1 wherein said instrument has an open end opposite said heat sink adapted to be inserted onto said neck.

9. A cryosurgical system as defined in claim 8 wherein said open end has a removable cover adapted to be mounted thereon, said cover having passages therein leading to the atmosphere, and filter means associated with said passages for evaporating any liquid refrigerant passing therethrough.

10. Apparatus as defined in claim 1 wherein said heat sink has an open interior and inwardly extending flange portions adapted to support the innermost end of said transfer means.

11. A cryosurgical system as defined in claim 1 where in a temperature sensing device is provided in said heat sink, and electrical means are associated with said temperature sensing device for displaying the temperature within said heat sink.

12. A cryosurgical instrument comprising, a hollow tubular pencil-like housing, means defining a pair of radial partition means in said housing which cooperate with said housing to define a storage chamber therebetween, first valve means in one of said partition means for permitting the fiow of liquid refrigerant into said storage chamber to fill said storage chamber, an elongated hollow probe secured in a fluid-tight manner to one end of said housing, a small passage in the other of said partition means in communication with said storage chamber, a valve means in said small passage for controlling the flow of liquid refrigerant through said passage, a small diameter tube disposed within said probe and having one end in communication with said small passage with the opposite end disposed in said probe for receiving refrigerant from said storage chamber and for spraying liquid refrigerant in said probe, and passage means in communication with said hollow probe for conducting the evaporated refrigerant from said probe to a point exterior of said housing.

13. A cryosurgical instrument as defined in claim 12 wherein a third partition means is provided in said housing to define a second chamber therein, said passage means communicating with said second chamber, porous filter means in said second chamber to insure that said refrigerant is completely evaporated before being discharged to the atmosphere, and means connecting said second chamber to the atmosphere.

14. Apparatus as defined in claim 12 wherein said first valve means is disposed adjacent the opposite end of said housing, and discharge means are provided to actuate said valve means to permit said storage chamber to be manually discharged therethrough.

15. A cryosurgical instrument as defined in claim 14 wherein said discharge means includes porous filter means through which the refrigerant must pass before it is discharged from said first valve means into the atmosphere.

16. A cryosurgical instrument as defined in claim 12 wherein said probe is removably secured to said housing separate from said small tube for removal and replacement of said probe without detaching said small tube.

17. A cryosurgical instrument as defined in claim 12 wherein said second valve means is manually opened prior to using the instrument and manually closed when cooling of said probe is no longer desired.

18. A cryosurgical system for performing surgical operations using very cold temperatures comprising, a base adapted for use with a small instrument, said base including a housing defining an interior chamber and having a cup-shaped bottom member with side wall means supported thereon and a cover thereon, said interior chamber adapted to receive container means for storing a liquid refrigerant, a valve assembly in said container, means defining a neck in the exterior surface of said cover for receiving the instrument, actuator means extending through said neck for cooperation with said valve assembly, and means for actuating said valve assembly to perrnit the liquid refrigerant to flow upwardly through said neck into the instrument.

19. A cryosurgical instrument as defined in claim 18 wherein partition means are provided in said housing adapted to support said container means, passage means in said partition means communicating with a space between said partition and said cup-shaped bottom member, porous filter means in said cup-shaped bottom member for insuring that refrigerant flowing through said passage means is evaporated before being discharged to the atmosphere.

References Cited UNITED STATES PATENTS 3,133,539 5/1964 Eidus 128399 3,190,081 6/1965 Pytryga 128-400 XR 3,259,131 7/1966 Kanbar et a1. 128-3031 L. W. TRAPP, Primary Examiner. 

1. A CRYOSURGICAL SYSTEM FOR PERFORMING SURGICAL OPERATIONS USING VERY COLD TEMPERATURES COMPRISING, A BASE, A SMALL INSTRUMENT ADAPTED TO BE SECURED TO SAID BASE, SAID INSTRUMENT INCLUDING AN ELONGATED TUBULAR HOUSING HAVING A HEAT SINK SECURED IN ONE END THEREOF, A PROBE SECURED IN SAID ONE END FOR TRANSFER OF HEAT FROM SAID HEAT SINK, SAID BASE INCLUDING MEANS FOR SUPPLYING A LIQUID REFRIGERANT, A VALVE ASSEMBLY IN SAID BASE FOR COOPERATION WITH SAID SUPPLY MEANS, A NECK IN THE EXTERIOR SURFACES OF SAID BASE ADAPTED TO RECEIVE AND HOLD SAID INSTRUMENT, ACTUATOR MEANS EXTENDING THROUGH SAID NECK FOR COOPERATION WITH SAID VALVE ASSEMBLY, MEANS FOR ACTUATING SAID VALVE ASSEMBLY TO PERMIT THE LIQUID REFRIGERANT TO FLOW UPWARDLY THROUGH SAID NECK INTO SAID INSTRUMENT, ANDD TRANSFER MEANS FOR CONDUCTING THE LIQUID REFRIGERANT FROM SAID NECK TO A POSITION ADJACENT SAID HEAT SINK AND FOR SPRAYING SAID LIQUID REFRIGERANT ONTO SAID HEAT SINK TO SUBSTANTIALLY REDUCE THE TEMPERATURE THEREOF. 